Figure 3. Homogenisation of cooked macroparticles and starch digestibility.

Light micrographs of homogenised macroparticles of chickpea (left) and wheat (right) captured before (a,b) and after 6 h (c,d) in vitro digestion, stained with 2.5% Lugol’s iodine solution. Scalebar = 50 μm. Intact macroparticles (1.85 mm) of chickpea and durum wheat endosperm were hydrothermally-cooked prior to homogenisation by UltraTurrax® for 30 s at 16.4 x 10³ rpm. Homogenisation caused cell separation in chickpea (a) and cell rupture in wheat (b). After 6 h incubation with amylase, the chickpea cells remained intact (c) while starch granules released from cells by homogenisation pre-treatment had been digested (c,d). Starch digestibility curves show the progress of starch digestion of hydrothermally-cooked intact and homogenised macroparticles of chickpea (e) and wheat (f). The digestions were performed in quadruplicate, and values are means with error bars as SEM. Significant differences between starch digestion from intact and homogenised particles are indicated (paired t-test), **p < 0.01, ***p < 0.001, and ‘ns’ not significant, p > 0.05. Curves were obtained by least squares regression to two-phase association equations and 95% confidence bands show the likely location of the true curve. R² values were 0.95 and 0.92 for intact and homogenised chickpea, and 0.98 and 0.81 for intact and homogenised durum wheat, respectively.